llvm/utils/TableGen/TableGen.cpp

#include "Record.h"
#include "Support/CommandLine.h"
#include <algorithm>

static cl::opt<std::string> Class("class", cl::desc("Print Enum list for this class"));
static cl::opt<bool>        Parse("parse");

void ParseFile();

RecordKeeper Records;

static Init *getBit(Record *R, unsigned BitNo) {
  const std::vector<RecordVal> &V = R->getValues();
  for (unsigned i = 0, e = V.size(); i != e; ++i)
    if (V[i].getPrefix()) {
      assert(dynamic_cast<BitsInit*>(V[i].getValue()) &&
	     "Can only handle fields of bits<> type!");
      BitsInit *I = (BitsInit*)V[i].getValue();
      if (BitNo < I->getNumBits())
	return I->getBit(BitNo);
      BitNo -= I->getNumBits();
    }

  std::cerr << "Cannot find requested bit!\n";
  abort();
  return 0;
}

static unsigned getNumBits(Record *R) {
  const std::vector<RecordVal> &V = R->getValues();
  unsigned Num = 0;
  for (unsigned i = 0, e = V.size(); i != e; ++i)
    if (V[i].getPrefix()) {
      assert(dynamic_cast<BitsInit*>(V[i].getValue()) &&
	     "Can only handle fields of bits<> type!");
      Num += ((BitsInit*)V[i].getValue())->getNumBits();
    }
  return Num;
}

static bool BitsAreFixed(Record *I1, Record *I2, unsigned BitNo) {
  return dynamic_cast<BitInit*>(getBit(I1, BitNo)) &&
         dynamic_cast<BitInit*>(getBit(I2, BitNo));
}

static bool BitsAreEqual(Record *I1, Record *I2, unsigned BitNo) {
  BitInit *Bit1 = dynamic_cast<BitInit*>(getBit(I1, BitNo));
  BitInit *Bit2 = dynamic_cast<BitInit*>(getBit(I2, BitNo));

  return Bit1 && Bit2 && Bit1->getValue() == Bit2->getValue();
}

static bool BitRangesEqual(Record *I1, Record *I2,
			   unsigned Start, unsigned End) {
  for (unsigned i = Start; i != End; ++i)
    if (!BitsAreEqual(I1, I2, i))
      return false;
  return true;
}

static unsigned getFirstFixedBit(Record *R, unsigned FirstFixedBit) {
  // Look for the first bit of the pair that are required to be 0 or 1.
  while (!dynamic_cast<BitInit*>(getBit(R, FirstFixedBit)))
    ++FirstFixedBit;
  return FirstFixedBit;
}

static void FindInstDifferences(Record *I1, Record *I2,
				unsigned FirstFixedBit, unsigned MaxBits,
				unsigned &FirstVaryingBitOverall,
				unsigned &LastFixedBitOverall) {
  // Compare the first instruction to the rest of the instructions, looking for
  // fields that differ.
  //
  unsigned FirstVaryingBit = FirstFixedBit;
  while (FirstVaryingBit < MaxBits && BitsAreEqual(I1, I2, FirstVaryingBit))
    ++FirstVaryingBit;

  unsigned LastFixedBit = FirstVaryingBit;
  while (LastFixedBit < MaxBits && BitsAreFixed(I1, I2, LastFixedBit))
    ++LastFixedBit;
  
  if (FirstVaryingBit < FirstVaryingBitOverall)
    FirstVaryingBitOverall = FirstVaryingBit;
  if (LastFixedBit < LastFixedBitOverall)
    LastFixedBitOverall = LastFixedBit;
}

static bool getBitValue(Record *R, unsigned BitNo) {
  Init *I = getBit(R, BitNo);
  assert(dynamic_cast<BitInit*>(I) && "Bit should be fixed!");
  return ((BitInit*)I)->getValue();
}

struct BitComparator {
  unsigned BitBegin, BitEnd;
  BitComparator(unsigned B, unsigned E) : BitBegin(B), BitEnd(E) {}

  bool operator()(Record *R1, Record *R2) { // Return true if R1 is less than R2
    for (unsigned i = BitBegin; i != BitEnd; ++i) {
      bool V1 = getBitValue(R1, i), V2 = getBitValue(R2, i);
      if (V1 < V2)
	return true;
      else if (V2 < V1)
	return false;
    }
    return false;
  }
};

static void PrintRange(std::vector<Record*>::iterator I, 
		       std::vector<Record*>::iterator E) {
  while (I != E) std::cerr << **I++;
}

static bool getMemoryBit(unsigned char *M, unsigned i) {
  return (M[i/8] & (1 << (i&7))) != 0;
}

static unsigned getFirstFixedBitInSequence(std::vector<Record*>::iterator IB,
					   std::vector<Record*>::iterator IE,
					   unsigned StartBit) {
  unsigned FirstFixedBit = 0;
  for (std::vector<Record*>::iterator I = IB; I != IE; ++I)
    FirstFixedBit = std::max(FirstFixedBit, getFirstFixedBit(*I, StartBit));
  return FirstFixedBit;
}

// ParseMachineCode - Try to split the vector of instructions (which is
// intentially taken by-copy) in half, narrowing down the possible instructions
// that we may have found.  Eventually, this list will get pared down to zero or
// one instruction, in which case we have a match or failure.
//
static Record *ParseMachineCode(std::vector<Record*>::iterator InstsB, 
				std::vector<Record*>::iterator InstsE,
				unsigned char *M) {
  assert(InstsB != InstsE && "Empty range?");
  if (InstsB+1 == InstsE) {
    // Only a single instruction, see if we match it...
    Record *Inst = *InstsB;
    for (unsigned i = 0, e = getNumBits(Inst); i != e; ++i)
      if (BitInit *BI = dynamic_cast<BitInit*>(getBit(Inst, i)))
	if (getMemoryBit(M, i) != BI->getValue())
	  return 0;
    return Inst;
  }

  unsigned MaxBits = ~0;
  for (std::vector<Record*>::iterator I = InstsB; I != InstsE; ++I)
    MaxBits = std::min(MaxBits, getNumBits(*I));

  unsigned FirstFixedBit = getFirstFixedBitInSequence(InstsB, InstsE, 0);
  unsigned FirstVaryingBit, LastFixedBit;
  do {
    FirstVaryingBit = ~0;
    LastFixedBit = ~0;
    for (std::vector<Record*>::iterator I = InstsB+1; I != InstsE; ++I)
      FindInstDifferences(*InstsB, *I, FirstFixedBit, MaxBits,
			  FirstVaryingBit, LastFixedBit);
    if (FirstVaryingBit == MaxBits) {
      std::cerr << "ERROR: Could not find bit to distinguish between "
		<< "the following entries!\n";
      PrintRange(InstsB, InstsE);
    }

#if 0
    std::cerr << "FVB: " << FirstVaryingBit << " - " << LastFixedBit
	      << ": " << InstsE-InstsB << "\n";
#endif

    FirstFixedBit = getFirstFixedBitInSequence(InstsB, InstsE, FirstVaryingBit);
  } while (FirstVaryingBit != FirstFixedBit);

  //std::cerr << "\n\nXXXXXXXXXXXXXXXXX\n\n";
  //PrintRange(InstsB, InstsE);

  // Sort the Insts list so that the entries have all of the bits in the range
  // [FirstVaryingBit,LastFixedBit) sorted.  These bits are all guaranteed to be
  // set to either 0 or 1 (BitInit values), which simplifies things.
  //
  std::sort(InstsB, InstsE, BitComparator(FirstVaryingBit, LastFixedBit));

  // Once the list is sorted by these bits, split the bit list into smaller
  // lists, and recurse on each one.
  //
  std::vector<Record*>::iterator RangeBegin = InstsB;
  Record *Match = 0;
  while (RangeBegin != InstsE) {
    std::vector<Record*>::iterator RangeEnd = RangeBegin+1;
    while (RangeEnd != InstsE &&
          BitRangesEqual(*RangeBegin, *RangeEnd, FirstVaryingBit, LastFixedBit))
      ++RangeEnd;
    
    // We just identified a range of equal instructions.  If this range is the
    // input range, we were not able to distinguish between the instructions in
    // the set.  Print an error and exit!
    //
    if (RangeBegin == InstsB && RangeEnd == InstsE) {
      std::cerr << "Error: Could not distinguish among the following insts!:\n";
      PrintRange(InstsB, InstsE);
      abort();
    }
    
    if (Record *R = ParseMachineCode(RangeBegin, RangeEnd, M)) {
      if (Match) {
	std::cerr << "Error: Multiple matches found:\n";
	PrintRange(InstsB, InstsE);
      }

      assert(Match == 0 && "Multiple matches??");
      Match = R;
    }
    RangeBegin = RangeEnd;
  }

  return Match;
}

static void PrintValue(Record *I, unsigned char *Ptr, const RecordVal &Val) {
  assert(dynamic_cast<BitsInit*>(Val.getValue()) &&
	 "Can only handle undefined bits<> types!");
  BitsInit *BI = (BitsInit*)Val.getValue();
  assert(BI->getNumBits() <= 32 && "Can only handle fields up to 32 bits!");

  unsigned Value = 0;
  const std::vector<RecordVal> &Vals = I->getValues();

  // Start by filling in fixed values...
  for (unsigned i = 0, e = BI->getNumBits(); i != e; ++i)
    if (BitInit *B = dynamic_cast<BitInit*>(BI->getBit(i)))
      Value |= B->getValue() << i;
  
  // Loop over all of the fields in the instruction adding in any
  // contributions to this value (due to bit references).
  //
  unsigned Offset = 0;
  for (unsigned f = 0, e = Vals.size(); f != e; ++f)
    if (Vals[f].getPrefix()) {
      BitsInit *FieldInit = (BitsInit*)Vals[f].getValue();
      if (&Vals[f] == &Val) {
	// Read the bits directly now...
	for (unsigned i = 0, e = BI->getNumBits(); i != e; ++i)
	  Value |= getMemoryBit(Ptr, Offset+i) << i;
	break;
      }
      
      // Scan through the field looking for bit initializers of the current
      // variable...
      for (unsigned i = 0, e = FieldInit->getNumBits(); i != e; ++i)
	if (VarBitInit *VBI =
	    dynamic_cast<VarBitInit*>(FieldInit->getBit(i))) {
	  if (VBI->getVariable()->getName() == Val.getName())
	    Value |= getMemoryBit(Ptr, Offset+i) << VBI->getBitNum();
	}	
      Offset += FieldInit->getNumBits();
    }

  std::cout << "0x" << std::hex << Value << std::dec;
}

static void PrintInstruction(Record *I, unsigned char *Ptr) {
  std::cout << "Inst " << getNumBits(I)/8 << " bytes: "
	    << "\t" << I->getName() << "\t" << *I->getValue("Name")->getValue()
	    << "\t";
  
  const std::vector<RecordVal> &Vals = I->getValues();
  for (unsigned i = 0, e = Vals.size(); i != e; ++i)
    if (!Vals[i].getValue()->isComplete()) {
      std::cout << Vals[i].getName() << "=";
      PrintValue(I, Ptr, Vals[i]);
      std::cout << "\t";
    }
  
  std::cout << "\n";// << *I;
}

static void ParseMachineCode() {
  unsigned char Buffer[] = { 0x55,             // push EBP
			     0x89, 0xE5,       // mov EBP, ESP
			     //0x83, 0xEC, 0x08, // sub ESP, 0x8
			     0xE8, 1, 2, 3, 4, // call +0x04030201
			     0x89, 0xEC,       // mov ESP, EBP
			     0x5D,             // pop EBP
			     0xC3,             // ret
			     0x90,             // nop
			     0xC9,             // leave
			     0x89, 0xF6,       // mov ESI, ESI
			     0xB8, 1, 2, 3, 4, // mov EAX, 0x04030201
			     0x68, 1, 2, 3, 4, // push 0x04030201
			     0x5e,             // pop ESI
			     0xFF, 0xD0,       // call EAX
			     0x85, 0xC0,       // test EAX, EAX
			     0xF4,             // hlt
  };
  
  std::vector<Record*> Insts;

  const std::map<std::string, Record*> &Defs = Records.getDefs();
  Record *Inst = Records.getClass("Instruction");
  assert(Inst && "Couldn't find Instruction class!");

  for (std::map<std::string, Record*>::const_iterator I = Defs.begin(),
	 E = Defs.end(); I != E; ++I)
    if (I->second->isSubClassOf(Inst))
      Insts.push_back(I->second);

  unsigned char *BuffPtr = Buffer;
  while (1) {
    Record *R = ParseMachineCode(Insts.begin(), Insts.end(), BuffPtr);
    if (R == 0) {
      std::cout << "Parse failed!\n";
      return;
    }
    PrintInstruction(R, BuffPtr);

    unsigned Bits = getNumBits(R);
    assert((Bits & 7) == 0 && "Instruction is not an even number of bytes!");
    BuffPtr += Bits/8;
  }
}


int main(int argc, char **argv) {
  cl::ParseCommandLineOptions(argc, argv);
  ParseFile();

  if (Parse) {
    ParseMachineCode();
    return 0;
  }

  if (Class == "") {
    std::cout << Records;           // No argument, dump all contents
  } else {
    Record *R = Records.getClass(Class);
    if (R == 0) {
      std::cerr << "Cannot find class '" << Class << "'!\n";
      abort();
    }

    const std::map<std::string, Record*> &Defs = Records.getDefs();
    for (std::map<std::string, Record*>::const_iterator I = Defs.begin(),
	   E = Defs.end(); I != E; ++I) {
      if (I->second->isSubClassOf(R)) {
	std::cout << I->first << ", ";
      }
    }
    std::cout << "\n";
  }
  return 0;
}